You get a +2 to one score of your choice and +1 to two others.

fiendlings mature at the same rate as humans but live a few years longer.

Tieflings are about the same size and build as humans. Your size is Medium.

Your base walking speed is 30 feet.

Warpfire and impossible starlight have changed your sight. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can also see through smoke and fog of any kind.

Choose Intelligence or Charisma when you create this character. That ability is your spellcasting ability for racial spells and mutation traits from this race.
You know one cantrip of your choice from the sorcerer, warlock, or wizard spell list. Starting at 3rd level, you can cast disguise self and alter self once with this trait and regain the ability to do so when you finish a long rest. You can also cast it with any spell slots you have available.

Choose two mutations from the Mutations of Change list below. Whenever you gain an Ability Score Improvement from your class, you can replace one mutation you know with a different mutation from the list.

Choose two of the following mutations.

Avian Eyes: One or more of your eyes becomes bright, birdlike, or impossibly faceted. You gain proficiency in Perception. In addition, you have advantage on Investigation checks.

Barbed Claws: Your hands, feet, or both bear hooked talons. Your claws are natural weapons, which you can use to make unarmed strikes. If you hit with them, they deal 1d4 slashing damage instead of the normal bludgeoning damage for an unarmed strike. These talons have the finesse property.

Gossamer Pinions: You possess vestigial wings, feathered fins, drifting membranes, or other gliding organs. When you fall, you can use your reaction to reduce any falling damage you take by an amount equal to five times your level. While falling, you can move up to 2 feet horizontally for every 1 foot you descend.

Many-Jointed Climber: Your limbs bend in ways they should not, or you grow extra gripping structures. You gain a climbing speed equal to your walking speed.

Warpflame Gland: Your blood, breath, or inner organs smolder with mutagenic fire. You have resistance to fire damage.

Mirrored Flesh: Your skin shimmers, refracts, or briefly becomes unreal when threatened. When a creature you can see hits you with an attack roll, you can use your reaction to roll 1d4 and subtract the number rolled from the attack roll, potentially causing the attack to miss. Once you use this trait three times, you can’t use it again until you finish a short rest.

Oracle’s Knots: Your body bears impossible knots of horn, feather, scar, or crystal that twitch with unreal foresight. When you fail an attack roll, ability check, or saving throw, you can roll 1d4 and add it to the roll, potentially turning failure into success. You can use this trait after seeing the roll but before the outcome is declared. Once you use this trait three times, you can’t use it again until you finish a short rest.

Prehensile Tail: You possess a tail, tendril, ribbon of flesh, or similar appendage with useful control. Your tail can manipulate simple objects, open an unlocked door, draw or stow a small item, pick up something from the ground, or hold an object. It can’t wield weapons, shields, or tools, and it can’t perform the somatic components of spells. You gain advantage on acrobatics checks.

Shifting Veil: Your outline blurs and warps as though reality struggles to keep you in one shape. You can cast silent image once with this trait and regain the ability to do so when you finish a long rest.

Spell-Quills: Your feathers, scales, eyes, or scars leak raw sorcery. You learn two additional cantrips of your choice from the sorcerer, warlock, or wizard spell list.

Third Eye of Change: A hidden eye, rune, or sensory organ opens somewhere upon your body. You can cast detect magic three times with this trait and regain the ability to do so when you finish a short rest. You can also cast it as if it was on your spell list if you can cast spells normally.

Whispering Tongues: Your voice carries layered meanings, or thoughts slip from you like hissing prophecy. You can communicate telepathically with any creature you can see within 30 feet of you. This telepathy doesn’t allow the creature to reply telepathically unless it has a similar ability.

You can speak, read, and write Common and one of the following of your choice: Abyssal, Infernal, Draconic, or Primordial.